In recent years, various types of communication terminals such as personal computers, mobile telephones, and smartphones have been used, and a user who owns a plurality of communication terminals generally uses each of them separately according to the purpose of its use. In such a case, the user needs to make a contract for using a communication line for each communication terminal. For example, a user who owns a mobile telephone and a smartphone needs to make a contract with a communication provider to use the communication line for each communication terminal. Therefore, the amount of the contract fee for using the communication line increases as the number of communication terminals owned by the user increases. Further, if a Machine to Machine (M2M) communication spreads in the future, the number of M2M devices managed by one company or one group would increase, and thus the amount of the contract fee for using the communication line, which is required for each M2M device to be managed, also increases.
For example, Non-Patent Literature 1 defined by the 3GPP, which is a standardization organization regarding a mobile communication network, discloses a network configuration for performing communication using a Machine Type Communication (MTC) device in the mobile communication network. The MTC device corresponds to an M2M device.
One possible solution to decrease the amount of the contract fee for using the communication line imposed on the user as described above is to provide a communication service that allows the user to use a plurality of communication terminals with a contract for using a single communication line. Since such a communication service allows a plurality of users to share a single communication line, this communication service also enables communication lines to be provided for users in developing nations or the like for a low cost.